This invention relates generally to a hole former assembly used to form a hole in a concrete sidewall, and more particularly relates to a reusable hole former assembly that aligns the center of the formed hole in the concrete sidewall with the center of an inlet or outlet opening of an invert embedded in the base of a manhole. The hole former assembly of the present invention is suitable for use in either wet casting or dry casting the base of the manhole with the inlet and/or outlet of the invert embedded in a sidewall of the base of the manhole. Several of the component parts of the hole former assembly of the present invention may be molded as a single unit and thereafter separated, thereby reducing certain manufacturing costs of the component parts.
During the initial development of a community, a series of networked conduits are required to pipe sanitary sewage and storm sewage away from the community to, for example, a processing, treatment, or drainage site. Sanitary sewage and storm sewage systems are typically comprised of a plurality of networked pipelines that are buried in roadways deep enough to minimize the effects of heavy vehicles passing over the roadways and also deep enough (for example, below the frost line) to avoid the negative effects of freezing temperatures. In order to provide access to the pipeline for inspection and maintenance, manholes or catch basins are periodically interconnected within the networked pipelines. The manholes and/or catch basins are buried beneath the earth""s surface, and typically below roadways, at depths of 10 feet or more.
When a manhole or catch basin is first constructed, it typically comprises a base, risers, cone, support frame and manhole cover or grate. The base includes a bottom with concentric sidewalls extending upward from the bottom. The lower portion of the base of the manhole is referred to as a canal-bed. The base of the manhole or catch basin structure may include one or more openings adapted to receive the pipeline, wherein the canal-bed includes a channel that directs fluid passing between the interconnected pipelines. This channel may be lined with a fluid impermeable invert or liner.
One or more hollow cylindrical risers rest atop the base sidewalls, thereby increasing the sidewall of the manhole to a desired height. The cone is hollow and is stacked atop the uppermost riser, wherein one end of the cone is sized to fit on top of the riser and the other end of the cone has a reduced diameter suitable for receiving and supporting the support frame on top of the cone.
The base, risers and cone of the manhole structures are typically comprised of mortared blocks or pre-cast with concrete and may weigh several tons. Of course, the overall size of the base, including the internal and external diameters of the base sidewalls affects both the cost to manufacture the base and the cost to construct the manhole. Thus, it is desirable to decrease the diameter of the base as much as practical. However, oftentimes communities will require that an unobstructed inner diameter of the base, risers, and access opening must be equal or exceed predefined minimums for rigidity, stability and access. Hence, the desire to reduce costs associated with the manhole may be limited by minimum size requirements.
Once the manhole or catch basin is constructed, fluids passing therethrough tend to deteriorate the structure. For example, sewage and putrid water are very acidic, and may comprise hydrogen sulfide and sulfuric acid. Over time, exposure to sewage or putrid water can damage the concrete of the canal-bed, base, and cone. In catch basins, road salt also has a similar affect on the canal-bed. This is due to the eventual breakdown of the concrete by the road salt, especially if the concrete is of poor quality. When repair or replacement of these manhole/catch basin structures is required, due to a deteriorated canal-bed, base or cone, the procedure is extremely expensive, time consuming, and difficult. A canal bed liner or invert reduces the amount of repairs and replacement of the underlying canal bed. The invert typically includes an inlet and/or outlet extending into the sidewall of the base. The connecting pipe extends through a hole formed in the sidewall and inserts into the opening of the inlet or outlet. When pre-casting the base, the weight of the wet or dry cast concrete tends to deform the opening of the inlet and/or outlet so that the connecting pipe does not insert and seal in the opening of the invert. Although iron casts or plugs have been used to form the hole in the sidewall during the casting process and reduce the deformation in the opening in the invert, the weight of the iron cast prohibits dry casting without deformation. Hence, there is a need for a hole forming assembling that reduces deformation during casting of the invert and the hole extending through the base sidewall.
A Casket may be utilized to seal the outer surface of the connecting pipe to the interior surface of the hole formed in the sidewall of the base, thereby preventing water from seeping into the base of the manhole through the hole formed in the sidewall. A portion of the gasket may be embedded into the concrete sidewall or an expansion ring may be utilized to press the gasket against the interior surface of the hole formed in the sidewall base. U.S. Pat. No. 4,565.347 issued to Ditcher, U.S. Pat. No. 4,916,799 issued to Skinner et al., and U.S. Pat. No. 5.624,123 issued to Meyers each describe a gasket, wherein a portion of the gasket is embedded into the interior surface of the hole formed in the sidewall base. For example, Ditcher describes a monolithic precast invert system, wherein a pin locks a gasket retainer assembly to the canal bed mold member. In order to remove the inner portion of the gasket retainer assembly described by Ditcher, the canal bed mold member must be removed. These references do not describe a hole former assembly suitable for embedding a gasket in the hole formed in the sidewall base in conjunction with lining the canal bed with a liner or invert. Hence, there is a need for a hole forming assembly that aligns with a liner of the canal bed and that may be removed from the formed hole after the base is cast. The present invention meets these and other needs that will become apparent from a review of the description of the present invention.
The present invention provides for a hole former assembly for forming a hole in a concrete sidewall during casting, wherein the hole is in alignment with the inlet or outlet opening of a canal bed liner. The hole former assembly of the present invention further holds a gasket in place during casting, wherein a portion of the gasket is embedded in the cured concrete inside the formed hole. In the preferred embodiment, the hole former assembly includes a first annular member, a second annular member, an invert alignment member, and a clamp assembly. The invert alignment member is adapted for engagement with the first annular member, wherein the invert alignment member engages either the inlet or outlet opening of the canal bed liner or invert prior to forming, the hole. The clamp assembly holds together the first annular member, second annular member and the invert alignment member. The gasket is held in place between the first and second annular members.
Without limitation, in the preferred embodiment the first and second annular members and the invert alignment member are molded as a single part and then subsequently separated. The material used to mold the part should resist bonding with concrete and not be degraded from contact with concrete. For example without limitation, a high molecular polyethylene or other polymeric material having the same or similar characteristics are particularly well suited materials.
The advantages of the present invention will become readily apparent to those skilled in the art from a review of the following, detailed description of the preferred embodiment especially when considered in conjunction with the claims and accompanying drawings in which like numerals in the several views refer to corresponding parts.